The overall objective of the Spectratyping Core is to perform the TCR Vp CDR3-size spectratype analysis on relevant samples supplied by program Projects, and provide expertise for data analysis and interpretation. This Core will conduct molecular evaluation of the T cell repertoires from the presented samples as they relate to immunological reconstitution and regulation, as well as both alloreactive and tumor-reactive responses following allogeneic blood and marrow transplantation (BMT) in both clinical and experimental settings. Because the Core leader has extensive experience with this technology this Core will serve as an interactive resource for several aspects of the three projects.